Re: [Patch] tmpfs: add fallocate support

[Cong Wang]

ä 2011å11æ15æ 19:23, Pekka Enberg åé:
> Hello,
>
> On Tue, Nov 15, 2011 at 10:42 AM, Amerigo Wang<amwang@xxxxxxxxxx>  wrote:
> > This patch adds fallocate support to tmpfs. I tested this patch
> > with the following test case,
> >
> >         % sudo mount -t tmpfs -o size=100 tmpfs /mnt
> >         % touch /mnt/foobar
> >         % echo hi>  /mnt/foobar
> >         % fallocate -o 3 -l 5000 /mnt/foobar
> >         fallocate: /mnt/foobar: fallocate failed: No space left on device
> >         % fallocate -o 3 -l 3000 /mnt/foobar
> >         % ls -l /mnt/foobar
> >         -rw-rw-r-- 1 wangcong wangcong 3003 Nov 15 16:10 /mnt/foobar
> >         % dd if=/dev/zero of=/mnt/foobar seek=3 bs=1 count=3000
> >         3000+0 records in
> >         3000+0 records out
> >         3000 bytes (3.0 kB) copied, 0.0153224 s, 196 kB/s
> >         % hexdump -C /mnt/foobar
> >         00000000  68 69 0a 00 00 00 00 00  00 00 00 00 00 00 00 00  |hi..............|
> >         00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
> >         *
> >         00000bb0  00 00 00 00 00 00 00 00  00 00 00                 |...........|
> >         00000bbb
> >         % cat /mnt/foobar
> >         hi
> >
> > Signed-off-by: WANG Cong<amwang@xxxxxxxxxx>
>
> What's the use case for this?

Hi, Pekka,

Systemd needs it, see http://lkml.org/lkml/2011/10/20/275.
I am adding Kay into Cc.

Thanks.
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